I might be missing something here, but if your talking about a demi wave type perm, then this just means using a milder perm lotion with larger perm rods to achieve a wave rather than a curl. If I'm right in you just wanting a wave, rather than a curl, you can just use your usual perm lotion with larger rods.
In the 80s, we regularly used the so called demi-wave perm lotion, but it was no different from the rest of them. It was just marketed at clients wanting a very loose perm.
If I've got the wrong end of the stick, just ignore my reply and wait for another geek to post on here. Hope I was of some help. xx